In practice it is known for road pavers to first roughly pre-adjust the height of the paving material heap in front of the distributing auger. The distribution of the paving material made by the distributing auger for the respective thickness of the cast layer which is varied by the paving screed is then also adjusted correctly during the casting process by adjusting the distributing auger together with the auger support in height direction at the rear side of the chassis of the towing vehicle. In the case of large working widths the distributing auger is extended by mounting distributing auger extensions. The extension screed parts of the paving screed are further extended accordingly by mounting extension parts. The distributing auger extensions are arranged together with channel sheet metal plates and supports in casting travelling direction ahead of the paving screed. The extension screed parts are arranged at guiding systems at the rear side of the base screed of the paving screed. The poured paving material has to be spread outwardly in front of the paving screed. During the casting process the poured paving material is dragged by the paving screed in casting travelling direction. Due to the arrangement of the extension screed parts at the rear side of the base screed, in this case, paving material heaps of different volumes exist. During the casting process and owing to high dragging resistance of the poured paving material very high forces are introduced into the guiding system of the extension screed parts, which forces cause paving screed distortions which frequently deteriorate the evenness of the produced road mat. The forces also finally have an undesirable limiting influence on the maximum working width of the paving screed. In order to reduce the height of the paving material poured in front of the extension screed parts and also in front of mounted paving screed extensions and in order to reduce the dragging resistance occurring there scraper blades are mounted in front of and at the paving screed extensions. The height position of the scraper blades can be adjusted in relation to the respective paving screed extensions in order to minimise the height or to correctly adjust the height of the poured paving material in front of the extension screed part and the paving screed extension, respectively.
Furthermore, road pavers are used in practice at which scraper blade sections are instead mounted at distributing auger extensions of the distributing auger. The distributing auger is fixed at the chassis at a height position which cannot be changed during a casting process. Holders for the scraper blade sections comprise different hole arrangements with oblong holes allowing to adjust the height position of the scraper blade sections relative to the distributing auger extensions only during a break of a casting process in order to optimally limit the height of the poured paving material for the paving screed, which paving material is then cast into the road mat by the extended extension screed part or a paving screed extension. However, the distribution and height of the paving material cannot be adjusted during a casting process corresponding to the respective thickness of the road mat.
Further prior art can be found in: DE 102 00 361 A1, DE 100 28 819 A1, DE 297 13 808 U1, EP 1 120 495 A.